Hey all,
I'm gonna step in now and give a few thoughts ... mainly in reply to Andrew (silentworks) post but also just general observations.
I agree with Andrew (silentworks) on the fact that this is a subject that's been broached a few times. I think (for the better as well) that we are a community of opinions ... we all strive for the better of MODX but also have different needs and wants. In the past, these discussions have fizzled out or (like this one was a few pages back) into a 'see who can throw the shit at the wall and make it stick better' conversation - please, we're all better than that. Everybody should have their say, nobody left out, and not one person made to feel like their say is being diminished.
For me, personally, I don't think xPDO is outdated ... it needs a few updates but it's certainly not outdated. I'd much rather spend a bit of time creating a XML schema (which sometimes actually makes you think a bit more about the data model you're creating) than not. That being said, I think Jason (opengeek) was or still is looking into not even needing the XML schema for xPDO - I don't want to be jumping the gun here or making assumptions, I just remember in some far distant part of my mind having that discussion.
Regarding the template engine, I do agree with a few of the previous posters that it's not a high priority to change. I can understand, I think, where you are coming from Andrew though ... this is something that should be discussed further indeed though ... what are the shortcomings of what we have now?
Onwards to ACLs ... bloody ACLs, haha! Bit like marmite, love 'em or hate 'em. I'd argue that, yes, ACLs are difficult to get to grips with but they're definitely not impossible. We (at MODX) are doing things with ACLs that you'd find hard to do with any other permissions system (definitely not possible with the Evo permission system). So, yes, the ACLs can be improved - a lot of feedback we get is in the presentation of those in the Manager, I think we've all acknowledged as a team they need to be presented better (and made a bit more accessible).
Onto Composer, yes and yes - we need to support Composer going forward in my opinion. Is it straightforward to do that at this point in time? Nope. That doesn't mean we can't look down the avenues of what it would take and start that from there. As far as Package Management, yes, people do confuse Package Management with Composer sometimes ... they are two very different things. I don't see Package Management as broken ... just needs a bit of attention in the right places. I mean, for one use-case, let's think about Marky Mark and his business model if we suddenly ditched Package Management :p
And we have the designer bit, oh lord, yes ... please do contribute to Matboard

I'm not even going to comment on the designer stuff, it's not my forte and I'd likely sound stupid even attempting to talk about it. I will say though, the decision to choose the next JS framework (if we do over something more home-grown) is a big one and not one to be taken lightly ... how many Extras out there now rely on ExtJS? Not that I think ExtJS is wonderful, but sometimes better the devil you know ... I'd like to see concepts, if anybody has any, that would mean we get the same kind of components (grids, trees etc.) that we need for the Manager without having to jump through hoops more than what we have with ExtJS ... and that's my parting challenge I leave to you all